Maritime vessels of various kinds must often navigate shallow waters. Visual observation is a principal technique relied upon in recognizing and steering clear of waters that are too shallow for ships to pass without risk of touching bottom or running aground. Visual observation, however, is an unreliable and limited technique. For example, the interplay of waves caused by surface winds, tides and changes in ambient lighting render it quite difficult for an observer on a ship consistently and reliably to identify waters ahead that are of insufficient depth to accomodate the vessel. This technique is also of little use at night. Other depth finding techniques include the use of plumb lines and sonar equipment. These apparatuses, however, only detect the depth of the water beneath the vessels themselves. Thus, in the event of encountering a rapid decrease in water depth, it is often too late for a pilot to arrest the movement of a vessel or to alter its course before it has encroached into unsafe waters. Where the vessel is under sail power it is even difficult to maintain a desired tack at speeds sufficiently slow for these types of methods. That all of these procedures normally require that vessels proceed slowly is in itself another limiting factor.
Accordingly, it is seen that a need exists and indeed has existed for many years for a method and system for detecting the depth of waters in the vicinity and particularly ahead of vessels underway, and for piloting vessels in shallow waters. It is to the provision of such methods and systems therefore that the present invention is primarily directed.